Surface morphologies of SnO2(110)
Surface morphologies of SnO2(110)
复制标题
DOI：
10.1016/s0039-6028(03)00357-1
复制
发表时间：
2003-04-10
期刊：
影响因子：
1.9
通讯作者：
Diebold, U
中科院分区：
文献类型：
--
作者：
Batzill, M;Katsiev, K;Diebold, U
使用扫描隧道显微镜（STM）、离子散射光谱（ISS）和低能电子衍射（LEED）研究了不同制备条件下SnO2（110）的表面形貌。在 10(-3) mbar 氧气中退火会产生 1 x 1 衍射图案。这种表面呈现出主要由沿着低折射率晶体方向的直阶梯边缘分隔开的阶地。阶地表现出高密度的缺陷。退火至 8·10 K 会导致表面氧损失，但表面保留 1 x 1 周期性。然而，小于单层高度的台阶表明在此温度下已经发生了表面原子的显着重新排序。退火到更高的温度或通过溅射和真空退火进行表面制备总是会导致衍射图案中的超结构和 ISS 中的低 [O]/[Sn] 比。对于 920 至 1050 K 之间的退火温度，观察到 c(2 x 2) 和 4 x 1 重构域共存。在这种情况下，小岛屿总是出现在地表。扩展阶地由 STM 以 4 x 1 的周期成像。这意味着 c(2 x 2) 结构与表面的岛屿相关。退火至 1100 K 仅导致形成 4 x 1 表面。该表面呈现出带有蜿蜒阶梯边缘的梯田和 4 x 1 表面结构的反相域边界。提出了一种用于这种重建的新模型，其中包括占据间隙表面位置的 Sn 原子。退火至 1180 K 会导致 4 x 1 结构碎裂，并且表面失去其长程有序。这会导致源自底层基材的 1 x 1 LEED 图案。具有子层间台阶高度的表面起伏可以通过频繁存在的堆垛层错和其他体缺陷来解释，这些缺陷还伴随着由于局部改变的 Sn/O 化学计量而导致的电子结构的变化。 (C) 2003 Elsevier Science B.V. 保留所有权利。
Scanning tunneling microscopy (STM), ion scattering spectroscopy (ISS), and low energy electron diffraction (LEED) was used to investigate the surface morphology of SnO2(110) for different preparation conditions. Annealing in 10(-3) mbar oxygen results in a 1 x 1 diffraction pattern. Such surfaces exhibit terraces separated predominantly by straight step edges along low index crystallographic directions. The terraces exhibit a high density of defects. Annealing to 8 10 K results in the loss of surface oxygen but the surface retains a 1 x 1 periodicity. Steps of less than monolayer-height, however, indicate that a significant reordering of the surface atoms occurs already at this temperature. Annealing to higher temperature or preparation of the surface by sputtering and vacuum annealing always results in a superstructure in the diffraction pattern and a low [O]/[Sn] ratio in ISS. For annealing temperatures between 920 and 1050 K co-existence of c(2 x 2) and 4 x 1 reconstructed domains is observed. In this regime small adislands are always present at the surface; extended terraces were imaged by STM with a 4 x 1 periodicity. This implies that the c(2 x 2)structure is associated with adislands at the surface. Annealing to 1100 K resulted in the formation of a 4 x 1 surface only. This surface exhibits terraces with meandering step edges and antiphase domain boundaries of the 4 x 1 surface structure. A new model for this reconstruction is proposed including Sn atoms occupying interstitial surface sites. Annealing to 1180 K results in the fragmentation of the 4 x 1 structure and the surface looses its long-range order. This causes a 1 x 1 LEED pattern originating from the underlying substrate. Surface undulations with sub-interlayer step heights are explained by the frequent presence of stacking faults and other bulk defects that are also accompanied by variations in the electronic structure due to a locally altered Sn/O stoichiometry. (C) 2003 Elsevier Science B.V. All rights reserved.